// MD5Calc.cpp: MD5Calc class.

#include "stdinc.h"
#include "MD5Calc.h"

const int _ReadBufSize = 1000000;

MD5Calc::MD5Calc()
{
	// don't alloc buffer here, only on request
	mp_s8ReadBuffer = 0;
}

MD5Calc::~MD5Calc()
{
	FreeBuffer();
}

void MD5Calc::FreeBuffer()
{
	delete [] mp_s8ReadBuffer;
}

/*********************************************************************/
//
//          calculate MD5 from a file of any size (also size = 0)
//          returns "" on file error
//
/********************************************************************/

char* MD5Calc::CalcMD5FromFile(const wchar_t *s8_Path)
{
	if (!mp_s8ReadBuffer)
		mp_s8ReadBuffer = new char[_ReadBufSize];
		
	MD5Init();
	
	// ++++++++++++ Read file block by block +++++++++++
	
	HANDLE h_File = CreateFile(s8_Path, GENERIC_READ, FILE_SHARE_READ, 0,
	                           OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
	                           
	if (h_File == INVALID_HANDLE_VALUE)
		return "";
		
	int s32_Size = GetFileSize(h_File, 0);
	
	while (s32_Size > 0)
	{
		unsigned long u32_Read = 0;
		if (!ReadFile(h_File, mp_s8ReadBuffer, _ReadBufSize, &u32_Read, 0))
		{
			CloseHandle(h_File);
			return "";
		}
		
		MD5Update((unsigned char*)mp_s8ReadBuffer, u32_Read);
		
		s32_Size -= u32_Read;
	};
	
	CloseHandle(h_File);
	
	// ++++++++++++ Signature --> String +++++++++++
	
	return MD5FinalToString();
}

/*********************************************************************/
//
//          calculate MD5 from a string
//
/********************************************************************/

char* MD5Calc::CalcMD5FromString(const char *s8_Input)
{
	MD5Init();
	MD5Update((unsigned char*)s8_Input, strlen(s8_Input));
	
	return MD5FinalToString();
}

/*********************************************************************/
//
//          Calculation functions
//
/*********************************************************************/

/*
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void MD5Calc::MD5Init()
{
	ctx.buf[0] = 0x67452301;
	ctx.buf[1] = 0xefcdab89;
	ctx.buf[2] = 0x98badcfe;
	ctx.buf[3] = 0x10325476;
	
	ctx.bits[0] = 0;
	ctx.bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void MD5Calc::MD5Update(unsigned char *buf, unsigned len)
{
	unsigned long t;
	
	/* Update bitcount */
	
	t = ctx.bits[0];
	if ((ctx.bits[0] = t + ((unsigned long) len << 3)) < t)
		ctx.bits[1]++;  /* Carry from low to high */
	ctx.bits[1] += len >> 29;
	
	t = (t >> 3) & 0x3f;    /* Bytes already in shsInfo->data */
	
	/* Handle any leading odd-sized chunks */
	
	if (t)
	{
		unsigned char *p = (unsigned char *) ctx.in + t;
		
		t = 64 - t;
		if (len < t)
		{
			memcpy(p, buf, len);
			return;
		}
		memcpy(p, buf, t);
		MD5Calc::byteReverse(ctx.in, 16);
		MD5Transform(ctx.buf, (unsigned long *) ctx.in);
		buf += t;
		len -= t;
	}
	/* Process data in 64-byte chunks */
	
	while (len >= 64)
	{
		memcpy(ctx.in, buf, 64);
		MD5Calc::byteReverse(ctx.in, 16);
		MD5Transform(ctx.buf, (unsigned long *) ctx.in);
		buf += 64;
		len -= 64;
	}
	
	/* Handle any remaining bytes of data. */
	
	memcpy(ctx.in, buf, len);
}

/*
 * Convert signature to CString
 */
char* MD5Calc::MD5FinalToString()
{
	unsigned char signature[16];
	MD5Final(signature);
	
	ms8_MD5[0] = 0;
	char s8_Temp[5];
	for (int i = 0; i < 16; i++)
	{
		sprintf(s8_Temp, "%02X", signature[i]);
		strcat(ms8_MD5, s8_Temp);
	}
	
	return ms8_MD5;
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void MD5Calc::MD5Final(unsigned char digest[16])
{
	unsigned count;
	unsigned char *p;
	
	/* Compute number of bytes mod 64 */
	count = (ctx.bits[0] >> 3) & 0x3F;
	
	/* Set the first char of padding to 0x80.  This is safe since there is
	    always at least one byte free */
	p = ctx.in + count;
	*p++ = 0x80;
	
	/* Bytes of padding needed to make 64 bytes */
	count = 64 - 1 - count;
	
	/* Pad out to 56 mod 64 */
	if (count < 8)
	{
		/* Two lots of padding:  Pad the first block to 64 bytes */
		memzero(p, count);
		MD5Calc::byteReverse(ctx.in, 16);
		MD5Transform(ctx.buf, (unsigned long *) ctx.in);
		
		/* Now fill the next block with 56 bytes */
		memzero(ctx.in, 56);
	}
	else
	{
		/* Pad block to 56 bytes */
		memzero(p, count - 8);
	}
	MD5Calc::byteReverse(ctx.in, 14);
	
	/* Append length in bits and transform */
	((unsigned long *) ctx.in)[14] = ctx.bits[0];
	((unsigned long *) ctx.in)[15] = ctx.bits[1];
	
	MD5Transform(ctx.buf, (unsigned long *) ctx.in);
	MD5Calc::byteReverse((unsigned char *) ctx.buf, 4);
	memcpy(digest, ctx.buf, 16);
	memzero(&ctx, sizeof(MD5Context));        /* In case it's sensitive */
}

/* The four core functions - F1 is optimized somewhat */

/* #define F1(x, y, z) (x & y | ~x & z) */
#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

/* This is the central step in the MD5 algorithm. */
#define MD5STEP(f, w, x, y, z, data, s) \
	( w += f(x, y, z) + data,  w = w<<s | w>>(32-s),  w += x )

/*
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */
void MD5Calc::MD5Transform(unsigned long buf[4], unsigned long in[16])
{
	register unsigned long a, b, c, d;
	
	a = buf[0];
	b = buf[1];
	c = buf[2];
	d = buf[3];
	
	MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
	MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
	MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
	MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
	MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
	MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
	MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
	MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
	MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
	MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
	MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
	MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
	MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
	MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
	MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
	MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);
	
	MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
	MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
	MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
	MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
	MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
	MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
	MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
	MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
	MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
	MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
	MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
	MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
	MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
	MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
	MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
	MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);
	
	MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
	MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
	MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
	MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
	MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
	MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
	MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
	MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
	MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
	MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
	MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
	MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
	MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
	MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
	MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
	MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);
	
	MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
	MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
	MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
	MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
	MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
	MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
	MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
	MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
	MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
	MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
	MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
	MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
	MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
	MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
	MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
	MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);
	
	buf[0] += a;
	buf[1] += b;
	buf[2] += c;
	buf[3] += d;
}

#ifdef sgi
#define HIGHFIRST
#endif

#ifdef sun
#define HIGHFIRST
#endif

#ifndef HIGHFIRST
void MD5Calc::byteReverse(unsigned char *, unsigned)
{
	// Nothing
}
#else
// Note: this code is harmless on little-endian machines.
void MD5Calc::byteReverse(unsigned char *buf, unsigned longs)
{
	unsigned long t;
	do
	{
		t = (unsigned long)((unsigned) buf[3] << 8 | buf[2]) << 16 |
		    ((unsigned) buf[1] << 8 | buf[0]);
		*(unsigned long *) buf = t;
		buf += 4;
	}
	while (--longs);
}
#endif
